I have a 2001 Ranger with the 2.5L Lima engine. I plan on doing my second tuneup at 150k, yet the truck came from the factory with half thread plugs - which I can no longer get, not even from the dealer.

I am afraid that if I replace my half thread plugs with full thread plugs, that the full thread plug will extend further into the combustion chamber. Any thoughts on this? Someone said that the full thread plug inserts like a half thread - no worries. Is this true? Do I need to use a torque wrench to install the full thread plugs?

Any feedback would be helpful and appreciated. Thanks in advance!

 

The distance between the sealing shoulder and the firing tip of the plug is the same on each style of plug, so so go ahead and use the full thread plugs.

Just be sure to use double platinum plugs from Motorcraft or AutoLite only.

 

Ford/Motorcraft don't make PP's anymore for that engine. As a matter of fact, Ford recommends fine wire plugs now.
I bought Autolite PP's for my 2.5 and they don't last as long as the Motorcraft PP's. Too bad so sad Ford decided that one. Next plug change with my 2.5 will be the Motorcraft fine wires

 

I'm not sure I completely understand the "half-thread" reference, but if it's what I think, then a tap should be used to chase the threads before screwing in full length plugs, or you chance stripping the threads in the head. Carbon will have filled the unused threads.

Grease the tap to catch any debris before threading it into the hole.

 

I'm with you bro. I have the same engine in my truck and can still buy the same type of plugs I did when I bought the truck new. I just look at the sparkplug chart and cross reference to others that are now being made for the engine. Half, Full.... They screw in the hole and the engine starts

 

I want to thank you all, for your input! I'll go and try the full thread plugs...I am assuming they screw in just the same?

To those who are unfamiliar with full thread / half thread, check out the below page:

Performance Mustang Parts Spark Plug Fully Threaded Spark Plugs Photo 1

 

Performance Mustang Parts Spark Plug Performance Spark Plugs Photo 2

 

OK, if you've been using half-length threads, it is highly recommended that you chase the threads before using full length thread plugs. If you don't, be very sensitive to the threading force required when you screw in the new plugs. If it starts feeling tight even though the plug isn't all the way in, then stop! You MUST clean the threads in the head.

 

Thanks, Reddog, for your helpful reply. Thing is, I am a shadetree mechanic on my best day; chasing the plug is a bit above my pay grade. In doing my next tuneup, I won't have to worry about metal filings going into the combustion chamber, will I?